Piezoelectric burner igniters and systems

ABSTRACT

Piezoelectric crystal type burner igniters of a single shot and multiple shot type are disclosed. The igniters utilize a piston for driving the hammer of the igniter from its armed position to its fired position in contact with the anvil of the crystal stack, and the piston is actuated and driven by pressurized fluid means that may be a combustible gas or liquid which is fed to the burner ignited through actuation of the igniter. Systems using the igniters to ignite auxiliary burners that in turn are used to ignite the main burner of a heater are also disclosed.

United States Patent 19] Mercer et al.

[ 1 PIEZOELECTRIC BURNER IGNITERS AND SYSTEMS [76] Inventors: Alan C. Mercer, 555 Gateway Dr.;

Owen R. Hilliard, 540 Gateway Dr., both of Merritt Island, Fla. 32952 22 Filed: Jan. 22, 1973 21 App]. No.: 325,747

11] 3,802,828 1 Apr. 9, 1974 3,634,706 1/1972 Kreuter 310/83 Primary Examiner-Edward G. Favors Attorney, Agent, or Firm-Roger L. Martin [5 7] ABSTRACT Piezoelectric crystal type burner igniters of a single shot and multiple shot type are disclosed. The igniters utilize a piston for driving the hammer of the igniter from its armed position to its fired position in contact with the anvil of the crystal stack, and the piston is actuated and driven by pressurized fluid means that may be a combustible gas or liquid which is fed to the burner ignited through actuation of the igniter. Systems using the igniters to ignite auxiliary burners that in turn are used to ignite the main burner of a heater are also disclosed.

28 Claims, 6 Drawing Figures PATENIEDAPR '9 m4 3802' 828 SHEET 1 (IF 4 PATENTEDAPR 9 I974 SHEET 2 [IF 4 PIEZOELECTRIC BURNER IGNITERS AND SYSTEMS BACKGROUND OF THE INVENTION The invention relates to igniters of piezoelectric-type spark producing devices and to burner ignition systems using such devices.

Piezoelectric spark producing devices for use in igniting combustible fuels are known in the art. Such devices have a hammer which is moved into forceful contact with the anvil component of a piezoelectric crystal stack that serves as a component of an open electrical circuit which is provided with a spark gap. When the crystal is deformed by the hammer blow a voltage is generated in the circuit of sufficient magnitude to create an are or spark in the gap area of the circuit. In most of such prior art devices the hammer is actuated and driven by mechanical components into forceful contact with the anvil.

A recent improvement in the art (see Laurent U.S. Pat. No. 3,516,560) provides for the use of pneumatic pressure to arm and trigger a hammer actuating mechanism in an igniter that relies on mechanical means for driving the hammer into contact with the anvil componentof the crystal stack. The patentee under such circumstances utilizes a diaphragm to seal theactuating mechanism from the pressurized fluid source and the diaphragm provides an expandiblechamber that acts against a mechanical device for actuating the hammer drive component.

The use of disphragms and auxiliary triggering de- I vices in piezoelectric-type spark producing devices leads to complicated structures and extra parts that are subject to wear. Such uses also entail expensive assembling and manufacturing procedures andobviously reduce the reliability of such devices in actual use. A simple, reliable and inexpensive igniter and system that is responsive to fluid pressure conditions is accordingly needed in the market area.

There is also need in the art for fluid pressure responsive burner ignition systems that utilize a piezoelectrictype ignition device which is actuated by other than manual or electrical means so as to reduce installation costs and/or maintenance and labor involved in the use of such systems.

One of the problems which is resident in the art is that of igniting combustible liquid fuels such as fuel oil.

Such fuels are normally more difficult to ignite than gaseous fuels. Ignition systems which utilize an auxiliary source of gaseous fuel for igniting an auxiliaryburner that is arranged to ignite the fuel supplied the main burner ofthe primary heating device have been suggested. Such systems however are usually expensive to install and require complicated and expensive means for connecting the fuel sources to the respective burners in a proper sequence and in addition they usually continue to consume fuels from both sources during the operation of the main burner.

SUMMARY OF INVENTION In accord with one aspect of the invention, apiezoelectric type spark producing igniter is equipped with a hammer that is and linearly movable with a piston that is actuated and driven by fluid pressure from a combustible fuel source. Detent means is provided for retaining the piston-hammer in an armed condition until sufficient fluid pressure builds up in the piston chamber to propel the hammer into forceful contact with the crystal stack. In a preferred ignition system, the igniter is used in conjunction with a fuel gas burner that is equipped with a pressure regulating gas inlet orifree that is connected by a suitable passageway forming conduit to the pressurized source of gaseous fuel. The passageway to the piston chamber of the igniter is connected to the pressurized gas fuel source by suitable conduits which communicate with thefeed conduit to the burner inlet orifice. By virtue of the arrangement, when the gaseous fuel is fed to the burner, the upstream pressure condition at the burner orifice is simultaneously imposed upon the piston of the igniter so that when the pressure on the piston exceeds the forces restraining movement thereof, the detent is disengaged and the piston is actuated and driven by the pressurized gaseous fuel to a position at which the hammer impacts against the anvil of the piezoelectric stack. The piezoelectric stack is, of course, connected in an open circuit having a spark gap which is located in the combustion chamber of the burner and upon impact generates the necessary voltage to produce a spark in the gap and thus ignite the gaseous fuel in the burner.

In the preferred embodiment the piston-hammer arrangement remains in a fired position so long as a suitable pressure condition is maintained in the feed conduit to the burner and biasing means in the form of a coiled compression spring is provided for returning the piston to the armed position when the pressure condition is sufficiently reduced.

As will be subsequently seen, the ignition system may be used for igniting the main burner of a liquid fuel fired heating device and that certain aspects of the invention contemplate the modification of the system to facilitate actuating and driving the piston component of the igniter by and in response to pressure conditions in the fuel supply at the main burner of the heating device.

Yet another aspect of the invention has to do with an igniter of the piezoelectric spark producing type that is capable of providing a multitude of blows against the anvil component of th crystal pack and thus provide successive sparks in the spark gap of the device. In accord with this aspect of the invention, the piston is equipped'with a valve component that closes the inlet passageway to the piston chamber when the piston is at the armed position and in an arrangement where the piston defines opposite end compartments in the piston chamber. The piston is also equipped with a hammer component and both the valve and hammer are fixed to the piston and linearly movable therewith. The piston carries a suitable seal and has an orifice which interconnects the two compartments in the piston chamber. The housing for the piston has yet another orifice which communicates with the exterior of the housing and with the chamber compartment at the inlet end of the chamber and this orifice is preferably of smaller size than the piston orifice. The igniter in this instance has a biasing means which may be in the form of a coiled spring that constantly urges the piston into the armed position at which the inlet passageway to the chamber is closed. The arrangement is such that the biasing force of the spring is overcome when the pressure differential between that in the fluid inlet passageway and that in the chamber exceeds a predetermined pressure differential so that the valve is unseated. When this compartment at the inlet side of the piston and the piston is thrust to a fired position at which the hammer impacts with the anvil of the piezoelectric stack and thus produces a spark in the gap of the open circuit. The piston orifice, under such circumstances, is adapted to limit the passage of gas between the compartments during the forceful movement of the piston to the fired position and thereafter permit the pressure conditions in the compartments to equalize. This permits the biasing means to return the piston to the armed position. The discharge orifice which communicates with the compartment at the inlet side of the piston, being preferably smaller than the piston orifice, is adapted to limit the passageof gas out of the chamber during the forceful movement and returnv of the piston but after the valve again seats itself permits the pressure to reduce in the piston chamber to the point at which the predeter mined pressure differential is againestablished and the valve component is actuated to repeat the cycle.

In the preferred embodiment themultiple shot igniter is also used in conjunction with a gas fired burner which is equipped with a pressure regulating gas inlet orifice and the fluid inlet passage to the pistonchamber is similarly connected to the gas feed line to the inlet orifice of the burner. i 7

Other aspects of the invention have to do with burner ignition systems which utilize a valve mechanism for connecting and disconnecting the igniter and burner to a pressurized source of gaseous fuel. Certain of these other aspects contemplate a valve mechanism which is responsive to pressure conditions of the fuel at the main burner of the heating device utilizing the ignition system, as will be subsequently seen. Yet other aspects of the invention contemplate the use of a valve mechanism that is equipped with a gas accumulating chamber that serves as a limited source of pressurized gaseous fuel for combustion in the burner of the system and for actuating the igniter component of the system. The valve mechanism under such circumstances is connected to a pressurized source of gaseous fuel and is so structured upon actuation as to disconnect the accumulating chamber from the pressurized fuel source and simultaneously connect the accumulating chamber with theburner and igniter'co mponents of the system so that the fuel consumed by the burner for ignition purposes is limited'by that which is accumulated in the accumulating chamber as will be'subsequently seen.

A general object of the invention is to provide improved piezoelectric-type spark producing igniters or devices. A particular object of the invention is to provide improved igniters of the type contemplated and which are actuatable in response to pressure conditions of a combustible fuel to be ignited. Yet another object of the invention is to provide simple acting, low-cost, fluid pressure responsive piezoelectric-type spark producing igniters that are readily adaptable for use in ignition systems which utilize asource of pressurized fuel that is ignited in a burner. Yet another object of the invention is to provide improved burner ignition systems for primary heating devices and which are .actuatable in response to pressure conditions of the fuel supplied to the heating device. Yet another object is to provide a fluid pressure actuated multiple shot piezoelectrictype igniter. Yet another object is to provide more reliable ignition system for heating devices. Other objects will be apparent from the following disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features which are believed to be characteristicofthis invention are setforth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which: a

FIG. 1 is an elevational view of the working end of a gas fired burning torch that is equipped with a piezoelectric spark producing igniter embodying certain aspects of the invention, certain parts being broken away and others depicted in longitudinal section;

FIG. 2 is a top view of the FIG. 1 device as seen along the Lines 22 thereof;

FIG. 3 is an enlarged view of a fragment of the igniter seen in FIG. 1;

FIG. 4 is a side elevational view of an ignition system utilizing the burner and igniter depicted in FIG. 1, the system being depicted as including a gas accumulating valve mechanism generally seen in vertical longitudinal section with certain parts broken away and as used in conjunction with aprimary heating device parts of which are illustrated in vertical section and others broken awa'y; 1

FIG. 5 shows another ignition system utilizing the gas accumulating valve mechanism and auxiliary burner seen in FIG.'4 but which is modified to include a multiple shot igniter in the system, the igniter, burner and gas accumulating valve mechanism of the system being generally depicted in longitudinal section and as seen in conjunction with the heating device illustrated in FIG. 4; and FIG. 6 is another side elevational view of a burner ignition system utilizing the gas accumulating valve mechanism, burner and igniter illustrated in FIG. 4 but wherein the valve mechanism and igniter are both coupled for response to fuel pressure conditions at the main burner of the heating device associated with the system.

DETAILED DESCRIPTION OF THE INVENTION Reference is.now'rriade to the drawings and more particularly to the embodiment depicted in FIGS. 1

through 3 inclusive. In this instance, certain aspects of the invention are shown as embodied in a conventional propane-type torch 10 that includes a container 11 for liquified propane, a conventional valve mechanism 12 that is secured to the neck of the container in communication with the pressurized gas fuel source internally thereof, and a conventional gaseous fuel burner 16.

The gas intake end 15 of burner 16 is connected to the valve mechanism 12 by means of a conduit 14 that forms a passageway for delivering the pressurized gaseous fuel from container 11 to the intake end of the burner. The valve of mechanism 12 is, of course, opened and closed by the manipulation of knob 13 so as to control the discharge of gaseous fuel from container 11.

Burner 16 includes a venturi compartment 17 which is located downstream froma pressure regulating gas inlet orifice component 18 of the burner. Component 18 is threaded in an internal annular flange component of burner 16 and at the upstream side of the flange the orifice component 18 is equipped with a suitable filter l9 to'prevent solid particles from being admitted to the orifice and thereby clogging the inlet. Upstream from the venturi constriction, burner 16 is provided with an air inlet 21 so as to admit combustion supporting oxygen to the burner. Downstream from compartment 17, burner 16 is provided wth radially projecting metal fins 24 that serve to attenuate and shape the flame in the burner combustion chamber 23. The burner depicted is of a conventional type found in the marketplace and it will be readily apparent to those skilled in the art that other suitable burners for gaseous fuels may be readily adapted for use in the embodiment generally depicted in the illustration.

The piezoelectric-type igniter is generally depicted at 25 and has a hollow housing 22 which is made up of a generally cylindrical body portion 29 that is equipped at its opposite ends with metal caps 38 and 56 respectively. The opposite ends of the body portion 29 are provided with external threads that are engaged by the caps 38 and 56 as seen in the drawings.

The body portion 29 has a cylindrical reduced end portion 30 and an enlarged cylindrical end portion 31 that are integrally joined as seen in the drawings, and the igniter 25 is mounted on the burner 16 of torch by means of an adaptor generally designated at 26. Adaptor 26 has a circular bore 27 and the flame end 28 of the burner is press fit in bore 27 while the enlarged portion 31 of body 29 is press fit in another circular bore 32 in adaptor 26 as seen in the figures.

The body portion 29 of housing 22 has an axially extending cylindrical bore that provides a piston chamber 34 in the reduced portion 30 and additionally provides an axially aligned compartment 33 in the enlarged portion 31 for housing the piezoelectric crystal stack 35. Stack 35 is provided with a narrow elongated lateral protuberance 36 that serves as a key for preventing rotational movement of the stack about the axis of the housing. This protuberance 36 fits in a keyway 37 that is milled in the internal wall of the enlarged section 31 as seen in the drawing.

The structure of the piezoelectric crystal stacks that may be used are well known in the art and any suitable type of crystal stack which upon deformation as by a hammer blow will generate sufficient voltage to produce a spark in the open circuit may-be employed. One terminal (not shown) of the crystal stack 35 is grounded to the metal housing 22 and the other terminal .(not shown) is electrically connected by an insulated electrical lead 42 to an electrode 43 which is en-' The piston chamber 34 houses a cylindrical piston 51 which is linearly movable along the axis of chamber 34 and integrally joined and fixed to a cylindrical hammer component of the igniter. The crystal stack 35 abuts the metal cap 38 in compartment 33 and is provided with an anvil 49 which is axially aligned for impact with the hammer 50 when the igniter is fired.

Chamber 34 has opposite ends 54 and 55 and the metal cap 56 at end 54 is provided with an axially aligned bore 57 that serves as a gas inlet passageway that communicates with the piston chamber. At the crystal stack end 55 of chamber 34, igniter 25 is provided with a coiled compression spring 52 that serves to bias the piston and hammer toward the inlet end 54 of the chamber and thus into the armed position designated at 66. One end of spring 52 surrounds the anvil 49 in abutting relation to the crystal stack 35 while the other end of spring 52 abuts the piston 51 in an arrangement where the hammer extends through adjacent convolutions 68 of the spring 52.

As seen in FIGS. 1 and 3, the perimeter of the cylindrical piston 51 is provided with an annular groove 69 in which an O-ring 70 is housed to provide a fluid tight seal between the gas inlet end of chamber 34 and the compartment 33 for the crystal stack. O-ring 70 is carried by piston 51 in sliding contact with the inner wall 53 that defines the piston chamber 34 of housing 22 as seen in the drawings.

Piston 51 is equipped with a detent 71 that is engageable with an annular recess or groove 62 in the inner wall 53 at the armed position 66 for the piston. Piston 51 has an open ended bore 61 that extends transversely to the path of movement of the piston along the axis of chamber 34 and bore 61 houses a coiled compression spring 63 of the detent 7-1. At the opposite ends of the bore the bore is equipped with a pair of spherical metal elements 64 and 65 and which are constantly biased into contact with wall 53. As seen in FIG. 3, the spherical components 64 and 65 of the detent 71 are arranged to seat in groove 62 at the armed position for the piston. Groove 62 is somewhat less than hemicircular in cross section and hence when sufficient pressure is applied to the piston in the direction of arrow 73 the spherical elements 64 and 65 are forced inwardly against the urgings of spring 63 to release the detent and permit movement of the piston to the tired position generally designated at 67. The cap 56 of housing 22 cased between its opposite ends in ceramic insulation that is housed in a cylindrical electrode tube designated at 40. The metal tube 40 is press fit at its opposite ends in aligned holes 44 and 45 in the burner tube and enlarged body section 31 respectively, and the end of the electrode is arranged in the combustion chamber 23 in spaced relationship to the flame attenuating veins 24 so as to provide a spark gap 47. The metal veins 24 are grounded tothe body of the igniter 25 and the gap 47 has a conduit-type adaptor 58 which is threaded in bore 57 and conduit 14 has another adaptor-type conduit that communicates with the passageway formed by the conduit. Adaptors 58 and 60 are interconnected by a flexible conduit 59 so as to provide'a passageway for gas between the inlet passageway for chamber 34 and 'the passageway formed byconduit 14.

The passageway provided by adaptor 58, conduit 59 and adaptor 60 is ofsufficient size that for practical purposes there is no pressure drop along the passageway, and hence, the pressure at the upstream end of orifice 18 and at the inlet end of chamber 34 are substantially the same during operation of the igniter.

1n the operation of the igniter equipped torch 10, manipulation of knob 13 to open the valve mechanism 12 will admit pressurized combustible gas to conduit 14. As the pressure builds up in conduit 14 due to the manipulation of knob 13, the gas will pass through orifice component 18 and thence through the venturi section and outwardly through the combustion chamber at the discharge end of the burner. The detent 71 is adapted and arranged to release the piston from looking engagement with the wall 53 when the pressure at the gas inlet 57 exceeds a predetermined amount sufficient to forcefully thrust the hammer in the direction of arrow 73 against the urgings of return spring 52. At the crystal stack end 55 of chamber 34 housing 22 has an opening 74 which communicates with the chamber and the exterior of the housing to facilitate the necessary ingress and egress of air to accommodate movement of the assembly and avoid pressurizing the compartment.

Once the pressure at the inlet is sufficient to release the detent 71 the piston 51 forcefully moves the hammer linearly in the direction of arrow 73 and to the fired position 67 at which the hammer strikes the anvil 49 of crystal stack 35. When this happens, the piezoelectric crystal stack is deformed by the impact and a sufficient voltage is developed in circuit 48 to induce a spark in gap 47 of sufficient intensity to ignite the gaseous air-fuel mixture in the combustion chamber of the burner 16. Thereafter, torch may be used in a conventional manner and during such use, the pressure in the piston chamber maintains the hammer in the tired position 67 against the urgings of the'return spring 52.

side'of the piston'and the return spring urges the piston back into the armed position 66 so that the spherical components 64 and 65 are again urged by spring com-' ponent 63 into groove 62 and thereby. retain the piston at the armed position.

In the event igniter 25 misfires and fails to ignite the H burner 16 the user of the torch merely has to close the valve mechanism 12, thereafter permit the pressure condition in conduit 14 to reach ambient conditions and following this,r'epeat the process.

Among the advantages to the igniter depicted in th embodiment illustrated in FIGS. 1 through 3 is the simplicity of the parts and movements involvedin actuating the piston without the need for auxiliary triggering devices.

Reference is now made to FIG. 4 and wherein the piezoelectric igniter 25 and burner 16 are illustrated as components of a burner ignition system 75. Burner 16 in this instance serves as an auxiliary burner for igniting the main burner 76 ofa heating device generally designated at 77. In addition to igniter 25 and,bumer 16, the ignition system 75 includes a valve mechanism 78 which is equipped with gas accumulating chamber and is mounted on the neck of a container 80 that provides a source of combustible gaseous fuel for the operation of the burner 16 and actuation of the igniter 25.

The heating device 77 associated with system 75 includes a cylindrical housing 81 for the main burner 76. Burner 76 includes an atomizing-type'orifice nozzle 82 of conventional structure in the embodiment illustrated and which is mounted on a nipple 83 that is connected to a T-type fitting 84. Fitting 84 is connectedto a liquid fuel feed line or conduit 85 that in turn is connected through suitable valves (not shown) to a pressurized source of liquid fuel, such as fuel oil. Burner 76 has a circular dispersion plate that is mounted in the housing 81 above nozzle 82 as by means of suitably spaced metal brackets 84. Feed line 85 extends to the pressurized liquid fuel source through a suitable opening 88 in housing 81 and the other side of the fitting 84 is connected to mechanism 78 by means ofa fluid conduit 89 so that mechanism 78 is actuated, as will be subsequently seen, by the hydraulic pressure in the line servicing burner 76.

Valve mechanism 78 has a metal housing 90 that includes a cylindrical body portion 92 and a metal cap 95 which threadingly engagesthe lower end of body portion 92. Body portion 92 has valigned cylindrical bores 94 and 98 that communicate along a radially extending internal wall 125 of housing 90. Bores 94 and 98 provide a gas accumulating chamber 107 in housing and the opposite end walls 126 and 127 that define the gas accumulating chamber are provided with aligned 1 bores 97 and 100 respectively. Bores 97 and 100 respectively serve as a gas inlet and outlet for the accumulating chamber 107. The upper end of body portion Cap 95 is integrallyformed with an opposite facing cap 96 and the latter is screwed on the neck of a propane container 80 that provides a source of gaseous fuel that is fed to the accumulating chamber. Cap 96 contains a conventional bayonet-type valve releasing insert which provides a passageway for the discharge of the combustible gaseous-fuel in container 80 to the gas inlet 97,to the accumulating chamber.

Mechanism 78 has an element 91 that is linearly movable along the axis of the chamber 107. Element 91 includes a conically shaped valve component 99 that is housed in the end bore 98 andserves as a-valve component of mechanism 78 and also includes a cylindrical component 104 that is offset from the internal readially extending wall 125 and serves as a piston component of mechanism 78. At the base of the element 91 the element is also provided with a generally cylindrical portion 115 that serves as another valve component as will be, subsequently seen. Components 99, 104 and 115 are integrally formed and thus fixed together and linearly movable along the axis of the chamber 107.

The apex'of the valve component 99 as seen in the drawings is arranged in working alignment with passageway 100 andas seen in FIG. 4 in a seated position in thepassageway which thereby closes the passageway and obstructs the passage of gas from the accumulating chamber to the burner. Component 99 has a cylindrical O-ring 112 provides a peripheral seal along the cylindrical wall of bore 94. As seen in 1 16.4, the piston 104 is formed integral with the valve component 99 and the arrangement is such that when the valve component 99 is seated in passageway 100, the piston is slightly offset from the internal wall 125 at the upper end of the bore 94. This arrangement provides a fluid tight compartment 106 between the opposite ends walls 126 and 127 of the accumulating chamber to which fluid may be admitted to actuate the mechanism. The cylindrical body portion 92 has a radially extending protuberance or boss which is provided with a radially extending bore 108 in which the end of conduit 89 is threaded. Here the housing is also provided with another passageway 110 which communicates with the fluid tight compartment 106 and bore 108 so as to provide :a fluid inlet for the passage of liquid fuel between the compartment and conduit 89.

q The lower valve component 115 is integrally connected to the piston 104 by means of an axially arranged reduced cylindrical center section 114 as seen in FIG. 4. The end wall 126 of chamber 107 has an annular groove which surrounds the gaseous inlet formed by bore 97 and which is provided with an O-ring 118. When element 91 is in the outlet closing position shown in solid lines in FIG. 4 at 128, inlet 97 is opened. On the other hand, when element 91 linearly moves to the broken line position designated at 129 the outlet'passage 100 is opened and valve component 115 comes into facial contact with O-ring 118 and thereby closes'the inlet passageway 94 to chamber 107.

As seen in FIG. 4, the conical arrangement of valve component 99 provides a compartment 111 at the outlet end of bore 98 when valve 99 is seated in the passageway. The arrangement of the center section 114 also provides another compartment 117 in bore 94. Compartments 111 and 117 are interconnected by a passageway 113 that extends through the piston 104 and valve 99. When element 99 is in position 128, valve component 115 is arranged to provide yet another compartment 102 at the gas inlet end of the accumulating chamber 107. Valve component 115 as seen in FIG. 4 has yet another passageway 119 that communicates with compartments 117 and 102 at its opposite ends.

When 'burner 76 is inoperative and the pressure in conduits 85. and 89 is at ambient conditions, element 9] assumes the solid line position shown in FIG. 4 at 128. Under such circumstances, the gas accumulating chamber 107 is connected to the pressurized source of gaseous fuel in container 80 and the pressure differential between the compartments 117 and 106 is such as to maintain valve 99 in a closed position with respect to the outlet passageway 100.

To ignite burner 76 through the use of the ignition system 75 inthe embodiment illustrated in FIG. 4, the liquid fuel feed line is connected to the pressurized source of liquid fuel as by opening a valve, not shown. As this happens, fuel is initially discharged from nozzle 82 into the combustion zone 123 of the primary heating device 77. Thereafter and as the pressure in conduit 89 builds up to a point at which the pressure in compartment 106 exerts a force on the piston in the direction of arrow 122 that exceeds that in the opposite direction for reasons of the gaseous pressure conditions in the accumulating chamber 107, element 91 is actuated and moved to position 129. At this position, valve component 115 closes the inlet passageway 97 and valve component 99 is in an open position with respect to theoutlet passageway 100.

Once the valve mechanism 78 has been actuated in response to the pressure conditions at the main burner and element 91 has moved to the broken line position 129, both the igniter 25 and burner 16 are connected to the accumulating chamber and hence to the source of gaseous fuel which has accumulated in the chamber 107. This permits the pressurized gas in compartment 117 to pass via the passageway 113 to compartment 111 and thence through the outlet to conduit 14.

Orifice 18 of burner 16 under such circumstances provides a restriction in the flow of the accumulated gas to the combustion chamber of burner 16 and initially imposes a pressure at the inlet end of igniter 25 which is sufficient to actuate and forcefully drive the hammer against the anvil component of the crystal stack as described in the previous embodiment. This provides a spark in the spark gap of the igniter circuit and which, of course, ignites the fuel in the combustion chamber of burner 16.

Burner 16 in the embodiment depicted in FIG. 4 serves as an auxiliary burner and continues to project a flame from the discharge end of the burner through the opening 124 in the heater housing 81 and thus into the combustion zone 123. This flame continues until the combustible gas in the accumulator chamber 107 is dissipated and the pressure drops toambient pressure conditions in conduit 14. The flame projected through opening 124, of course, ignites the main burner of heating device 77. i

As the pressure drops in conduit 14 due to the dissipation of the pressurized gas from chamber 107 the pressure in the piston chamber of igniter 25 reaches a point at which the biasing force of the return spring is sufficient to return the piston and hammer to the armed position as described in the previous embodiment.

Once the main burner 76 is ignited and the pressure in the gas accumulating chamber 107 has reached ambient conditions, element 91 continues to remain in the broken line position 129 under the influence of the liquid pressure conditions in compartment 106 and hence the inlet passage 97 remains closed by valve component 115. Thereafter when the main burner 76 is turned off, as by means of a valve action disconnecting the burner 76 with the pressurized liquid source of fuel, the pressure in compartment 106 diminishes and the gas pressure acting upon the face of valve component in passageway 97 actuates' the valve and moves the assembly 91 into the solid line position 128. As this happens, the pressurized gaseous condition in container 80 is again imposed in the gas accumulating compartment 107.

It will be readily apparent to those skilled in the art that igniter 25 is a single shot igniter and that occasional misfirings occur with piezoelectric igniters and wherein the spark produced in the spark gap fails to ignite the gaseous fuel. In the embodiment illustrated, this situation can be overcome when detected by simply reducing the pressure in the liquid fuel line to the point at which the gas pressure in the gas inlet 97 of the valve mechanism forces the element 91 into the solid line position 128 so as to recharge the chamber 107 with pressurized gaseous fuel. Thereafter the liquid fuel pressure to burner 76 can be elevated to the point at which element 91 moves in the direction of arrow 122 and into the broken line position 129 to repeat the ignition process.

Reference is now made to the embodiment illustrated in FIG. 5 and wherein the heating device 77 is seen as associated with an ignition system designated at 130.

The ignition system 130 includes the gas accumulating,

valve mechanism 78, burner 16 and in this instance, a multiple shot igniter tht is designated at 134.

The structure and operation of burner 16 and valve mechanism 78 will be obvious from the previously described embodiments, the valve mechanism 78 being similarly connected to a pressurized source of gaseous fuel in container 80 and by means of conduit 89 to the T-type fitting 84 of burner 76 so that actuation of valve mechanism 78 is similar to that previously described in conjunction with FIG. 4. The burner 16in this instance is connected to the gas outlet 100 of mechanism 78 by means ofa conduit 131 which is threaded at its opposite ends into the intake end of burner 16 and in the radially extending bore 93 of mechanism 78. Conduit 131, provides a passageway for delivering pressurized gaseous fuel from the accumulating chamber 107 of mechanism 78 to the pressure regulating gas inlet orifice 18 of burner 16. Conduit 131 has a T-type fitting 132 and the conduit 131 is connected to the inlet passageway of themultiple shot igniter 134 by means of another conduit designated at 133.

The igniter in this instance has a three piece housing 144 which includes cylindrical sections designated at 136 and 140 and a cylindrical cap component designated at 135. As seen in FIG. 5, section 140 is equipped at one end with a flange 141 that threadin gly engages the end of cylindrical section 136 while at the other end, section 140 is threadingly engaged bythe cap component 135 of the housing 144.

piston component 138, a hammer component 146 and a valve component 153; These components are integrally joined in the structure of the element and hence are linearly movable together during the operation of the igniter.

ln the assembled igniter, the elongated cylindrical hammer 146 is generally housed in the piston chamber 137 but nevertheless extends along the axis of the hous- Chamber and provides a fluid tight'seal between compartments 154 and 155 at the perimeter of the piston.

Housing section 136 has another axially aligned bore 152 that provides a fluid inlet to the piston chamber and more particularly to the end'compartment 154. The valve component 153 of outlet 139 has a truncated conical shape as seen in the drawing and is axially aligned with the inlet port 152 so that when the outlet 139 is in the armed position shown in solid lines in FIG. 5 and designated at 176 the inlet passageway 152 is closed. v

Compartments 154 and 155 are interconnected byan orifice passageway 156 that is shown in the form of a small bore which communicates with the compartments 154 and 155 at the opposite faces of the cylindrical piston 138. The housing section 136 is also equipped with another orifice which is designated at 157. This orifice provides a passageway for gasbetween compartment 154 and the exterior of the housing for reasons which will be subsequently explained The crystal stack 143 may again be of any suitable construction and has an anvil 158 which is aligned for impact by the hammer 146 when the element moves in the direction of arrow 159 from the armed position designated at 176 tothe fired position designated at 177. vHousing section 140 has a port 173 which communi cates with compartment 142 and the exterior of the housing so as to accommodate ingress and egress of air to the compartments during movement of the slideable element 139. n

The igniter 134 is mounted on the burner 16 via an adaptor 160 which is similar to that described with the embodiment shown in FIG. 1. Adaptor 160 has a bore 161 in which the barrel of burner 16 is press fit and yet another bore 162 in which section 140 of the housing is also press fit. One terminal of the crystal stack 143 is grounded to the metal housing of the igniter and the metal adaptor and barrel of burner 16 complete a conductive path from this terminal to the flame attenuating veins 24 of burner 16. The other terminal (not shown) of the crystal stack is electrically connected in the open circuit 168 to an electrode 163 that is housed and appropriately insulated between its opposite ends inan electrode tube designatedat 164. Tube 164 is press fit at its opposite ends into aligned bores in the burner and igniter housings as seen in the drawings and the end of electrode 163 is spaced from the attenuating veins 24 in the combustion chamber of burner 16 so as to provide a spark gap 167 in the open circuit 168.

Except for the operation of igniter 134, the operation of the ignition system 130 is similar to that described in conjunction with the embodiment shown in FIG. 4.

lutions of a coiled compression spring 172 that is axially aligned and housed in the compartment so that it bears against piston 138 and the chamber end wall formed by flange 145. Spring 172 constantly biases the element 139 toward the inlet end of the piston chamber 137 and the piston 138 has a peripheral groove which Thus, when the feed line to burner 76 is initially connected to the pressurized source of liquid fuel, the pressure in feed line 85 quickly builds up to the point at which the atomizing orifice component 82 is rendered operative and liquid particles of fuel are sprayed into the combustion zone 123. Thereafter at a pressure exceeding that at which the atomizing nozzle 82 is rendered operative, the pressure in the fluid tight compartment 106 of valve mechanism 78 exerts a force on the piston 104 in the direction of arrow 122 and which exceeds the opposing forces exerted on the element 91 by the pressurized gas in the mechanism 78 and hence the gas outlet passageway 100 is opened to establish a pressurized gas condition in conduits 131 and 133.

For reasons of the orifices 156 and 157 it will be understood by those skilled in the art that chamber 137 is at ambient pressure conditions when element 91 is initially actuated to establish the initial pressurized gas condition in conduits 131 and 133. Hence, whenthe pressure differential between that in passageway 152 and in chamber 137 is sufficient to exert a force on the valve component 153 that exceeds that determined by the spring 172, element 139 starts to move in the direction of arrow 159. This unseats the valve component 153 at the inlet port 152 and establishes the pressurized condition in compartment 154. As such, a greater surface of the element 139 is exposed to the pressurized condition and the element is thrust in the direction of arrow 159 so that the hammer 146 is caused to impact against the anvil 158 of crystal stack 143 as the element arrives at the fired position 177. This forceful thrust of the hammer against the anvil 158 of course deforms the crystal stack and generates a voltage in circuit 168 which provides a spark in gap 167.

The piston orifice 156 functions as a pressure regulating orifice which limits the passage of gas from compartment154 to compartment 155 during the thrust of the element 139 from its armed position 176 to its fired position 177 so that the full benefit of the pressure differential between the compartments is substantially realized once the valve component 153 is unseated. The orifice 156 however thereafter permits the gas in compartment 154 to bleed into compartment 155 so that the pressure differential across the piston is reduced to the point at which the spring 172 returns the element from its fired position to its armed position 176. Orifice 157 also serves as a pressure regulating orifice that limits'the passage of gas from compartment 154 to the exterior of the housing and is preferably smaller in size than that of orifice 156. When spring 172 returns the element from its fired position 177 to its armed position 176 it will be appreciated by those skilled in the art that as the valve component 153 seats itself in passageway 152, the pressure conditions in passageway 152 and in compartment 154 are substantially equal. Orifice 157 however then permits the pressurized gas in chamber 137 to bleed out to the exterior of the housing. As such, the pressure in chamber 136 reduces and a point is reached at which the pressure differential between that in the inlet 152 and that in the chamber 137 is again sufficient to overcome the force of spring 172 so that the firing cycle is again repeated. This repetitive firing is, of course, continued until such'time as the pressure in the gas accumulating chamber of valve mechanism 78 is reduced to the point at which the forces of spring 172 can no longer be overcome.

During the operation of'tl'ie igniter 134, the gas in burner 16 of course is ignited and projects a flame through the opening 124 of the heating device 77 and henceignites the fuel discharged intothe combustion zone 123 from the orifice nozzle 82. The accumulating valve'mechanism 78 of course remains in position 129 until such time as the pressureat'the burner 76 is sufficiently'reducedto permitthe element 91 to move to the gas outlet closed position '128 under the influence of the gas pressure in'container 80.

The embodiment shown in FIG. of course has the advantage that if the gas in burner 16 is not ignited by the initial shot that produces the spark in gap 167 there is a high probability that it will be ignited during one or more of the subsequent firing cycles which transpire until the gas is dissipated from the accumulating chamber 107.

Reference is now made to FIG. 6 and wherein the single shot igniter 25, burner 16 and valve mechanism 78 are shown as connected in an ignition system 180 in which the igniter 25 is actuated in response to the fluid pressure of the fuel fed to the main burner 76 of heating device 77.

In system 180 the T-type fitting 84 of burner 76 is connected by a conduit 181 to a T-type fitting 182 in a conduit 183 that is connected at its opposite ends and communicates with a fluid tight compartment 106 of valve mechanism 78 and the inlet port 57 of the single shot igniter 25. The gas outlet of mechanism 78 on the other hand is connected by a conduit 184 with the gas intake end of burner 16 so as to provide a passageway for the delivery of accumulated gas'in the mechanis 78 to the burner.

To ignite the burner 76, utilizing the system 180 depicted in FIG. 6, feed line 85 is initially connected as by means of a valving action to the pressurized source of liquid fuel for the burner 76. As the pressure builds up'in the burner 76 orifice nozzle 82 is rendered operative and particles of fuel are projected into the combustion zone 123 of the heating device 77. Thereafter as the pressure further builds up at burner 76, mechanism 78 is actuated in response to the increased pressure so that the inlet passage to the gas accumulating chamber is closed by the valve action. The detent arrangement for the single shot igniter 25 in this system 180 is adapted and arranged to release the slideable element when the fluid pressure at theinlet passageway exceeds that required to actuate the valve mechanism 78 to permit the passage of gas to burner 16. Hence, valve mechanism 78 is actuated to permit gas to pass to burner 16 before the igniter 25 is actuated to provide a spark in the gap of the igniter circuit to ignite the fuel in the burner. This of course againproduces a flame which is projected to the opening 124 of heating device 77 and ignites the liquid fuel being projected from nozzle 82 into the combustion chamber 123. The burner 76 of the heater 81 is, of course,.shut off again by disconnecting the conduit from the pressurized source of fuel oil. As the pressure thereafter reduces in the conduit 18] the return spring of igniter 25 returns the firing element to its armed position and permits the slideable element of mechanism 78 to close the gas outlet port from the accumulating chamber and simultaneously open the inlet port. It is thus apparent that the igniters illustrated can be actuated by either pneumatic or hydraulic pressure.

While only certain preferred embodiments of this invention have been shown and described by way of illustration, many modifications will occur to those skilled in the art and it is, therefore, desired that it be understood that it is intended herein to cover all such modifications as fall within the true spirit and scope of this invention.

What is claimed as new and what it is desired to secure by Letters Patent of the United States is:

1. An igniter comprising an open electrical circuit having a spark gap and piezoelectric means deformable upon impact to produce a spark in the gap, a housing having a piston chamber with opposite ends, a piston housed in the chamber and linearly movable between anarmed position at one of said ends and another position in the chamber, hammer means fixed to and movable with the piston, means biasing the piston toward said one of said ends, and releasable detent means retaining said piston at said armed position; said piezoelectric means having an anvil aligned for impact with the hammer means at the other position for the piston, and said housing having a passageway communicating with the chamber at said one of said ends for admitting pressurized fluid thereto to thereby drive said piston from said armed position to said other position.

2. An igniter in accord with claim 1 where said detent means is mounted on and movable with said piston.

3. An igniter in accord with claim 2 where said housing has an internal wall that defines said chamber, and where said detent means is engageable with a recess in said wall at said armed position.

4. An igniter in accord with claim 3 where said piston has a bore extending transversely to the path of linear movement of the piston, and where said detent means comprises compression spring means housed in said bore, and an element biased by said compression spring into engagement with said recess at the armed position for the piston. i

5. An igniter in accord with claim 2 where said hous ing has an internal wall that defines saidchamber, and wheresaid igniter further comprises seal means slidably engaging said wall and mounted on and movable with the piston.

6. An igniter in accord with claim 1 where said biasing means comprises a coiled compression spring housed in the chamber at said other of said opposite ends, and where said hammer means is elongated and extends through convolutions of saidcoiled compression spring.

7. An igniter in accord with claim 6 where said housing has an internal wall that defines said chamber, where said detent means is mounted on and movable with said piston, where said piston has a bore extending transversely to the path of linear movement of the piston,'where said detent means comprises compression spring means housed in said bore, and an element biased by said compression springinto engagement with a recess in said wall at the armed position for the piston, and where said igniter further comprises seal means engaging said wall and mounted on and movable with the piston.

8. In combination an ignite'r'in accord with claim 1,

i a gaseous fuel burner having a pressure regulating gas orifice, and gaseous conduit means communicating,

with the housing passageway and with the passageway forming means that communicates with said inlet orifice; said spark gap being located in said combustion chamber. v

10. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising an igniter in accord with claim 1, an auxiliary gaseous fuel burner arranged uponignition to ignite fuel supplied said main burner from said first pressuized fuel source, and a second pressurized source of gaseous fuel; said auxiliary gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said inlet orifice for delivering pressurized gaseous fuel from said second pressurized source to said inlet orifice, gaseous conduit means communicating with the housing passageway and with fice; said spark gap being located in said combustion with the housing passageway and with the passageway v forming means that communicates with said inlet orithe passageway forming means that communicates 'with said inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressure conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.

11. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising an igniter in accord with claim 7, an auxiliary gaseous fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first pressurized fuel source, and a second pressurized source of gaseous fuel; said auxiliary gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said inlet orifice for delivering pressurized gaseous fuel from said second pressurized source to said inlet orifice, gaseous conduit means communicating with the housing passageway and with the passageway forming means that communicates with said inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressure conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.

12. An ignition system in accord with claim 10 where said valve mechanism includes a housing having a gas accumulating chamber that provides said second pressurized source of gaseous fuel and has opposite end walls, a gas outlet communicating with the accumulating chamber at one of said end walls and withsaid passageway forming means, and a gas inlet communicating with the accumulating chamber at the other of said end walls; where said system includes a third pressurized source of fuel that is connected with said gas inlet; and where said valve mechanism further includes a piston located in the accumulating chamber between said gas outlet and said gas inlet and being linearly movable between first and second positions therefor, a first valve component fixed to the piston of the mechanism and arranged to close said gas outlet at said first position and to open said gas outlet at said second position, and a second valve component fixed to and movable with the piston of the mechanism and arranged to close said gas inlet at said second position and to open said gas inlet at said first position; said gas accumulating chamber having an internal wall and said piston of the mechanism being arranged in the gas accumulating chamber with respect to said internal wall to therein define a fluid tight compartment, and said mechanism housing having a fluid inlet communicating with said fluid tight compartment and said fluid conduit means whereby said mechanism piston is moved to said second position in response to pressure conditions of fuel supplied to the main burner from said first source.

13. An ignition system in accord with claim 12 where said first valve component is adapted and arranged to define a compartment at the gas outlet end of the accumulating chamber, where said second valve component is offset from the other of said end walls at said first position for the mechanism piston and defines a compartment at the gas inlet end of the accumulating chamber, and where said mechanism has passageway means interconnecting the respective compartments at the gas inlet and gas outlet ends of the accumulating chamber.,

14. An igniter comprising an open electrical circuit having a spark gap and piezoelectric means that upon impact is deformable to generate a spark in said gap, a housing having a piston chamber with opposite ends, a piston linearly movable in the chamber between an armed position and another position and being offset from said opposite ends at its armedposition to thereby define oppositeend compartments in the chamber, a

hammer extending through one of said compartments and being fixed to and movable with the piston, and biasing means located in said one compartment and biasing said piston toward the other of said compartments;

said piezoelectric means having an anvil arranged for being actuatable in response to a predetermined pressure differential between that in the inletpassageway and that in said one compartment to thereby admit pressurized fluid to said other compartment and forcefully move said piston toward said other position, said piston orifice being adapted to limit the passage of gas between said compartments during said forceful movement of the piston and to thereafter permitthe pressure conditions in said compartments to equalize whereby said biasing means returns said piston. to said armedposition, and said discharge orifice being adapted to limit thepassage of gas from the chamber to the exterior of the housing duringsaid forceful'movement and return of said piston and to thereafter permit said predetermined pressure differential to be-established for again actuating said valve component.

15. An igniter in accord with claim 14 where said housing has an internal wall that defines said chamber, and where said igniter further comprises seal means engaging said wall and mounted on and movable with said piston.

16. An igniter in accord with claim 14 where said biasing means comprises a coiled compression spring, and where said hammer is elongated and extends through convolutions of said coiled compression spring.

17. An igniter in accord with claim 15 where said biasing means comprises a coiled compression spring, and where said hammer is elongated and extends through convolutions of said coiled compression spring.

18. In combination an igniter in accord with claim 14, a gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber, a pressurized source of gaseous fuel, means forming a passageway commnicating with said gas inlet orifice for delivering pressurized gaseous fuel from said source to said inlet orifice, and gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice; said spark gap being located in said combustion chamber.

19. In combination an igniter in accord with claim 17, a gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber, a pressurized source of gaseous fuel, means forming a passageway communicating with said gas inlet orifice for delivering pressurized gaseous fuel from said source to said inlet orifice, and gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice; said spark gap being located in said combustion chamber.

20. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising, an igniter in accord with claim 14, an auxiliary gas fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first source, and a second pressurized source of gaseous fuel; said auxiliary burner hacing a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said gas inlet orifice for delivering pressurized gaseous fuel from said second source to said gas inlet orifice, gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressurized conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.

21. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising, an igniter in accord with claim 17, an auxiliary gas fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first source, and a second pressurized source of gaseous fuel; said auxiliary burner having a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway commnicating with said gas inlet orifice for delivering pressurized gaseous fuel from said second source to said gas inlet orifice, gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressurized conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.

22. An ignition system in accord with claim 20 where said valve mechanism includes a housing having a gas accumulating chamber that provides said second pressurized source of gaseous fuel and has opposite end walls, a gas outlet communicating with the accumulating chamber at one of said end walls and with said passageway forming means, and gas inlet communicating with the accumulating chamber at the other of said end walls; where said system includes a third pressurized source of fuel that is connected with the gas inlet and the accumulating chamber, where said valve mechanism further includes a piston located in the accumulating chamber between the gas inlet and gas outlet thereof and being linearly movable between first and second positions therefor, a first valve component fixed to the piston of the valve mechanism and arranged to close the gas outlet of the accumulating chamber at said first position and to open such gas outlet at said second position and a second valve component fixed to and movable with the piston of the mechanism and arranged to close the gas outlet at said second position and to open the gas inlet at said first position; said piston of the mechanism and-said first valve componentbeing arranged in the gas accumulating chamber to therein define a fluid tight compartment between said piston and said gas outlet, and said mechanism housing having a fluid inlet communicating with said fluid tight chamber and the fluid conduit means whereby said mechanism piston is moved to said second position in response to pressure conditions of fuel supplied to the main burner from said first source.

23. An ignition system in accord with claim 22 where the first valve component is adapted and arranged to define a compartment at the gas outlet end of the accumulating chamber, where said second valve component is offset from the other of said end walls at said first position for the mechanism piston and defines a compartment at the gas inlet end of the accumulating chamber, and where said valve mechanism has passageway means interconnecting the respective compartments at the gas inlet and gas outlet end of the accumulating chamber.

24. In a piezoelectric igniter having a hammer which is movable between an armed position and a fired position, and an open circuit with a'spark gap and piezoelectric means having an anvil arranged for impact with thehammer at said fired position, the improvement comprising a housing having a chamber with a fluid inlet opening, and piston means located in the chamber and actuatable in response to pressurized fluid admitted to the chamber through said inlet opening for driving the hammer from its armed position to its fired position.

25. The improvement in accord with claim 24 further comprising means biasing the hammer toward its armed position.

26. The improvement in accord with claim 25 further comprising releasable detent means retaining the piston means at a predetermined position in the chamber and being releasable at a predetermined fluid pressure in said inlet opening.

' 27. In a piezoelectric igniter having a hammer which is movable between an armed position and a fired position, and an open circuit with a spark gap and piezoelectric means having an anvil arranged for impact with the hammer at said fired position, the improvement comprising a housing having a chamber with a fluid inlet opening, piston means arranged for linear reciprocating movement in the chamber and actuatable to successively drive the hammer from its armed position to its fired position in response to pressurized fluid delivered to said inlet opening, valve means movable with the piston means and arranged to close the chamber inlet opening when the hammer is at said armed position, and means biasing the valve means into said closed position. v

28. The improvement in accord with claim 27 where said piston means is arranged to define separate compartments in the chamber when said valve means is in exterior.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,802,828 Dated April 9, 1974 Inventm-(S) Alan C. Mercer and Owen R. Hilliard It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

UNITED STATES PATENT OFFICE -.2- CERTIFICATE OF CORRECTION Patent No. 3,802,828 Dated April 9, 1

lnventm-(s) Alan C. Mercer and Owen R. Hilliard It is certified that error appears in the above-identified patent and that said Letters Patent are hereby-corrected as shown below:

' II no I I25 H 52 I28 I 34 I74 I72 3 W 1/0 I 145/55 #5 I /22 729 15/ 175 I07 115 I 12 is 11a 95 i 7 do rr -64 l l as I. z s F UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,802,828 Dated April 1 Inventor(s) Alan C. Mercer and Owen R. Hilliard It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Figure 4, lead lines have been provided for characters 106 and 125.

In Figure 4, the line demarking the end surface 99 at the upper end of port 113 has been completed.

In Figure 4 the line denoting the surfaces at right-hand end of members 25 and 26 has been completed.

In Figure 5 the reference lines for characters 137, 139,

145, 147, 155 and 176 have been directed to the proper surfaces.

In Figure 5, the lines defining the bores of port 157 and 173 have been added in the proper location.

In Figure 5, the lines defining surfaces 104 and 107 have been completed so that the formal drawings conform to the informal drawings and specification, both correct as originally filed.

In Figure 5, the valve 153 of element 139 has been shown in a seated position in inlet 152.

Signed and Scaled this thirt Day Of January 1976 [SEAL] A ttest:

RUTH C. MASON Arresting Officer C. MARSHALL DANN Commissioner ofPaIenls and Trademarks 

1. An igniter comprising an open electrical circuit having a spark gap and piezoelectric means deformable upon impact to produce a spark in the gap, a housing having a piston chamber with opposite ends, a piston housed in the chamber and linearly movable between an armed position at one of said ends and another position in the chamber, hammer means fixed to and movable with the piston, means biasing the piston toward said one of said ends, and releasable detent means retaining said piston at said armed position; said piezoelectric means having an anvil aligned for impact with the hammer means at the other position for the piston, and said housing having a passageway communicating with the chamber at said one of said ends for admitting pressurized fluid thereto to thereby drive said piston from said armed position to said other position.
 2. An igniter in accord with claim 1 where said detent means is mounted on and movable with said piston.
 3. An igniter in accord with claim 2 where said housing has an internal wall that defines said chamber, and where said detent means is engageable with a recess in said wall at said armed position.
 4. An igniter in accord with claim 3 where said piston has a bore extending transversely to the path of linear movement of the piston, and where said detent means comprises compression spring means housed in said bore, and an element biased by said compression spring into engagement with said recess at the armed position for the piston.
 5. An igniter in accord with claim 2 where said housing has an internal wall that defines said chamber, and where said igniter further comprises seal means slidably engaging said wall and mounted on and movable with the piston.
 6. An igniter in accord with claim 1 where said biasing means comprises a coiled compression spring housed in the chamber at said other of said opposite ends, and where said hammer means is elongated and extends through convolutions of said coiled compression spring.
 7. An igniter in accord with claim 6 where said housing has an internal wall that defines said chamber, where said detent means is mounted on and movable with said piston, where said piston has a bore extending transversely to the path of linear movement of the piston, where said detent means comprises compression spring means housed in said bore, and an element biased by said compression spring into engagement with a recess in said wall at the armed position for the piston, and where said igniter further comprises seal means engaging said wall and mounted on and movable with the piston.
 8. In combination an igniter in accord with claim 1, a gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber, a pressurized source of gaseous fuel, means forming a passageway communIcating with said inlet orifice for delivering pressurized gaseous fuel from said source to said inlet orifice, and gaseous conduit means communicating with the housing passageway and with the passageway forming means that communicates with said inlet orifice; said spark gap being located in said combustion chamber.
 9. In combination an igniter in accord with claim 7, a gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber, a pressurized source of gaseous fuel, means forming a passageway communicating with said inlet orifice for delivering pressurized gaseous fuel from said source to said inlet orifice, and gaseous conduit means communicating with the housing passageway and with the passageway forming means that communicates with said inlet orifice; said spark gap being located in said combustion chamber.
 10. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising an igniter in accord with claim 1, an auxiliary gaseous fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first pressuized fuel source, and a second pressurized source of gaseous fuel; said auxiliary gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said inlet orifice for delivering pressurized gaseous fuel from said second pressurized source to said inlet orifice, gaseous conduit means communicating with the housing passageway and with the passageway forming means that communicates with said inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressure conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.
 11. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising an igniter in accord with claim 7, an auxiliary gaseous fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first pressurized fuel source, and a second pressurized source of gaseous fuel; said auxiliary gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said inlet orifice for delivering pressurized gaseous fuel from said second pressurized source to said inlet orifice, gaseous conduit means communicating with the housing passageway and with the passageway forming means that communicates with said inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressure conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.
 12. An ignition system in accord with claim 10 where said valve mechanism includes a housing having a gas accumulating chamber that provides said second pressurized source of gaseous fuel and has opposite end walls, a gas outlet communicating with the accumulating chamber at one of said end walls and with said passageway forming means, and a gas inlet communicating with the accumulating chamber at the other of said end walls; where said system includes a third pressurized source of fuel that is connected with said gas inlet; and where said valve mechanism further includes a piston located in the accumulating chamber between said gas outlet and said gas inlet and being linearly movable between first and second positions therefor, a first valve component fixed to the piston of the Mechanism and arranged to close said gas outlet at said first position and to open said gas outlet at said second position, and a second valve component fixed to and movable with the piston of the mechanism and arranged to close said gas inlet at said second position and to open said gas inlet at said first position; said gas accumulating chamber having an internal wall and said piston of the mechanism being arranged in the gas accumulating chamber with respect to said internal wall to therein define a fluid tight compartment, and said mechanism housing having a fluid inlet communicating with said fluid tight compartment and said fluid conduit means whereby said mechanism piston is moved to said second position in response to pressure conditions of fuel supplied to the main burner from said first source.
 13. An ignition system in accord with claim 12 where said first valve component is adapted and arranged to define a compartment at the gas outlet end of the accumulating chamber, where said second valve component is offset from the other of said end walls at said first position for the mechanism piston and defines a compartment at the gas inlet end of the accumulating chamber, and where said mechanism has passageway means interconnecting the respective compartments at the gas inlet and gas outlet ends of the accumulating chamber.
 14. An igniter comprising an open electrical circuit having a spark gap and piezoelectric means that upon impact is deformable to generate a spark in said gap, a housing having a piston chamber with opposite ends, a piston linearly movable in the chamber between an armed position and another position and being offset from said opposite ends at its armed position to thereby define opposite end compartments in the chamber, a hammer extending through one of said compartments and being fixed to and movable with the piston, and biasing means located in said one compartment and biasing said piston toward the other of said compartments; said piezoelectric means having an anvil arranged for impact by the hammer at the other position of the piston, said housing having a fluid inlet passageway communicating with said other compartment, and a discharge orifice communicating with said other compartment and with the exterior of the housing, said igniter further comprising a valve component fixed to and movable with the piston and being arranged in said other compartment to close said fluid inlet passageway at the armed position of the piston, said piston having orifice means interconnecting said compartments for the passage of gas therebetween, said valve component being actuatable in response to a predetermined pressure differential between that in the inlet passageway and that in said one compartment to thereby admit pressurized fluid to said other compartment and forcefully move said piston toward said other position, said piston orifice being adapted to limit the passage of gas between said compartments during said forceful movement of the piston and to thereafter permit the pressure conditions in said compartments to equalize whereby said biasing means returns said piston to said armed position, and said discharge orifice being adapted to limit the passage of gas from the chamber to the exterior of the housing during said forceful movement and return of said piston and to thereafter permit said predetermined pressure differential to be established for again actuating said valve component.
 15. An igniter in accord with claim 14 where said housing has an internal wall that defines said chamber, and where said igniter further comprises seal means engaging said wall and mounted on and movable with said piston.
 16. An igniter in accord with claim 14 where said biasing means comprises a coiled compression spring, and where said hammer is elongated and extends through convolutions of said coiled compression spring.
 17. An igniter in accord with claim 15 where said biasing means comprises a coiled compression spring, and where said hammer is elongateD and extends through convolutions of said coiled compression spring.
 18. In combination an igniter in accord with claim 14, a gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber, a pressurized source of gaseous fuel, means forming a passageway communicating with said gas inlet orifice for delivering pressurized gaseous fuel from said source to said inlet orifice, and gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice; said spark gap being located in said combustion chamber.
 19. In combination an igniter in accord with claim 17, a gaseous fuel burner having a pressure regulating gas inlet orifice and a combustion chamber, a pressurized source of gaseous fuel, means forming a passageway communicating with said gas inlet orifice for delivering pressurized gaseous fuel from said source to said inlet orifice, and gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice; said spark gap being located in said combustion chamber.
 20. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising, an igniter in accord with claim 14, an auxiliary gas fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first source, and a second pressurized source of gaseous fuel; said auxiliary burner hacing a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said gas inlet orifice for delivering pressurized gaseous fuel from said second source to said gas inlet orifice, gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressurized conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.
 21. An ignition system for igniting the main burner of a heating device that is supplied with fluid combustible fuel from a first pressurized fuel source comprising, an igniter in accord with claim 17, an auxiliary gas fuel burner arranged upon ignition to ignite fuel supplied said main burner from said first source, and a second pressurized source of gaseous fuel; said auxiliary burner having a pressure regulating gas inlet orifice and a combustion chamber; said system further comprising means forming a passageway communicating with said gas inlet orifice for delivering pressurized gaseous fuel from said second source to said gas inlet orifice, gaseous conduit means communicating with said fluid inlet passageway and with the passageway forming means that communicates with said gas inlet orifice, a valve mechanism for connecting said second pressurized source with said passageway forming means, and fluid conduit means interconnecting said valve mechanism and the main burner for actuating said valve mechanism in response to pressurized conditions of fuel supplied the main burner from said first source; said spark gap being located in said combustion chamber.
 22. An ignition system in accord with claim 20 where said valve mechanism includes a housing having a gas accumulating chamber that provides said second pressurized source of gaseous fuel and has opposite end walls, a gas outlet communicating with the accumulating chamber at one of said end walls and with said passageway forming means, and gas inlet communicating with the accumulating chamber at the other of said end walls; where said system includes a third pressurized source of fuel that is connected with thE gas inlet and the accumulating chamber, where said valve mechanism further includes a piston located in the accumulating chamber between the gas inlet and gas outlet thereof and being linearly movable between first and second positions therefor, a first valve component fixed to the piston of the valve mechanism and arranged to close the gas outlet of the accumulating chamber at said first position and to open such gas outlet at said second position and a second valve component fixed to and movable with the piston of the mechanism and arranged to close the gas outlet at said second position and to open the gas inlet at said first position; said piston of the mechanism and said first valve component being arranged in the gas accumulating chamber to therein define a fluid tight compartment between said piston and said gas outlet, and said mechanism housing having a fluid inlet communicating with said fluid tight chamber and the fluid conduit means whereby said mechanism piston is moved to said second position in response to pressure conditions of fuel supplied to the main burner from said first source.
 23. An ignition system in accord with claim 22 where the first valve component is adapted and arranged to define a compartment at the gas outlet end of the accumulating chamber, where said second valve component is offset from the other of said end walls at said first position for the mechanism piston and defines a compartment at the gas inlet end of the accumulating chamber, and where said valve mechanism has passageway means interconnecting the respective compartments at the gas inlet and gas outlet end of the accumulating chamber.
 24. In a piezoelectric igniter having a hammer which is movable between an armed position and a fired position, and an open circuit with a spark gap and piezoelectric means having an anvil arranged for impact with the hammer at said fired position, the improvement comprising a housing having a chamber with a fluid inlet opening, and piston means located in the chamber and actuatable in response to pressurized fluid admitted to the chamber through said inlet opening for driving the hammer from its armed position to its fired position.
 25. The improvement in accord with claim 24 further comprising means biasing the hammer toward its armed position.
 26. The improvement in accord with claim 25 further comprising releasable detent means retaining the piston means at a predetermined position in the chamber and being releasable at a predetermined fluid pressure in said inlet opening.
 27. In a piezoelectric igniter having a hammer which is movable between an armed position and a fired position, and an open circuit with a spark gap and piezoelectric means having an anvil arranged for impact with the hammer at said fired position, the improvement comprising a housing having a chamber with a fluid inlet opening, piston means arranged for linear reciprocating movement in the chamber and actuatable to successively drive the hammer from its armed position to its fired position in response to pressurized fluid delivered to said inlet opening, valve means movable with the piston means and arranged to close the chamber inlet opening when the hammer is at said armed position, and means biasing the valve means into said closed position.
 28. The improvement in accord with claim 27 where said piston means is arranged to define separate compartments in the chamber when said valve means is in said closed position and including a first compartment for receiving pressurized fluid admitted to the chamber through said inlet, where said piston means has orifice means interconnecting said separate compartments for therebetween restricting the flow of pressurized fluid admitted to the chamber, and said housing having orifice means interconnecting the exterior of the housing and said first compartment for restricting the passage of pressurized fluid from the first compartment to said exterior. 